As it is known by those skilled in the art, the irrigation systems known nowadays present as their main problem the stop and go intermittent movement of the support towers, needed to align the overhead pipeline spans and to compensate the travelled distance difference in the system of the central pivot, wherein the outer tower travels through a distance greater than the inner ones.
The pipelines are provided with water outlets with sprayers along the whole length, these pipelines being of various diameters according to the area size to be irrigated and the water amount to be applied, which varies from culture to culture. However, today, the ones that have an irrigation system, besides using it to irrigate the plants, also uses it for the application of agricultural pesticides and for the application of nutrients necessary for the plants.
The pipelines are provided with water outlets with sprayers along the whole length, these pipelines being of various diameters according to the area size to be irrigated and the water amount to be applied, which varies from culture to culture. The spans are suspended by movable towers that may have variable height due to the culture to which the equipment is designated, the spans are coupled to each other and may have variable length according to the need of the area to be irrigated and are moved by gear motors that drive by means of cardans the wheel gears, which in turn drive the pneumatic wheels that move the structure. In the case of the central pivot, an overhead structure turns about the pivot central tower, forming an irrigated area in the form of a circle. In the case of the linear irrigation system, the towers are dislocated in alignment with each other, linearly forming an irrigated area in the form of a rectangle. For the alignment between the towers, there is a microswitch driving device that when driven due to the misalignment moves the tower through the driving of the motor reducer that is initiated in the nominal speed. The alignment device consists of a metallic bar situated between both lances and coupled to a cam which drives the set of two microswitches, the service microswitch and the emergency microswitch. The service microswitch drives the gear motor set in a direction (e.g. clockwise) when closing the contact of the microswitch, through the cam, which is coupled to the control bar and which in turn is coupled to the immediately after span, when the orientation direction of the irrigation system is reverted, (e.g. counterclockwise), the microswitch drives the gear motor when opening the contact of the microswitch (the orientation direction of the towers is selected by the operator in the central panel), while the emergency microswitch functions as to deactivate the equipment when there is an extreme misalignment that will hinder the operations of the irrigation system. The microswitches have a deadband which is the dead state of the electric contact between closed and open or opened and close. This phenomenon is called deadband or hysteresis. In a set of many joined spans of an irrigation system, these deadbands are added and can induce an arc in the set of various spans, that is, the lances are not perfectly aligned to each other. This arc induced in the set of various spans may induce great tensile or compression pressures between the spans, causing mechanical fatigue in all of the set. These tensile or compression efforts affect mainly the central tower, making it possible to induce its displacement, pulling the tower set that is leaded in concrete blocks on the ground.
Due to technical reasons, it is necessary in spray irrigation to allow the system to move in low speeds, in a way that the percent timer is, for example, adjusted in 50%, which means that the final tower remains, during the one minute period, 30 seconds in operation and 30 seconds stationary, thereafter, the front towers will remain idle for a longer time. This final tower is also called the control tower. There is no sensor, once no angular offset of a subsequent movable tower needs to be registered herein.
The current spray irrigation systems that make the towers stop and go partially solve the problem of misalignment between the overhead pipeline spans and the different distances the towers have to travel through in the central pivot system. However, they do not solve problems with the great mechanical efforts that cause wear in the structural components and the problems of movement due to the stops and start-ups, which also imposes the very low displacement speed of the irrigation set. These constant stops and start-ups induce a non-uniform distribution of water blade in the soil to be irrigated, resulting in the same phenomenon during the application of liquid fertilizers and agricultural pesticides, along with water. In the stops periods of the motors determined by the alignment sensors of the movable towers, a greater precipitation of water and the products diluted in it takes place in this stop location, resulting in an excessive irrigation, causing losses of production and water by deep percolation, losses of nutrients by lixiviation, making it easy for culture diseases to arise, causing the costs increase, with water, energy, fertilizers and agricultural pesticides waste and increase of the soil contamination by the products excess in the stop locations. These problems tend to aggravate as the speed of the pivot reaches its lowest and/or consequently higher will be the blade determined by the regulation of the per centimeter relay.